1. Field of the Invention
This invention relates to an improved blade arrangement for mounting two blades of a rotary mowing machine on a common shaft with the cutting edges of both blades in substantially the same plane. In particular, it relates to an improved arrangement for mounting two blades on a common drive shaft in such a way that the cutting edges of both blades are not only in the same plane, but those of one blade are angularly located midway between those of the other.
2. The Prior Art
The concept of mounting two rotary mowing blades on a common shaft and at a right angle to each other has been suggested before in some of the following U.S. patents: U.S. Pat. Nos. 2,877,619 Benson et al., 2,926,867 Chadwick, 3,382,653 De Buigne, 3,343,350 Freedlander et al., 3,918,241 Stillions, 4,257,214 Ferguson et al., and 4,292,791 Lalonde. However, none of the prior art has suggested a mounting arrangement that places the cutting edges of both blades in a common plane. Doing so results in a neater cut, speeds up the mowing operation by allowing the machine to be moved forward at a greater speed while still making a neat cut. It also increases the vacuum ability of the mowing structure, thus blowing the cut vegetation to the outlet of the mowing machine with greater force and dispersing the grass farther, if the cut grass is not being captured in a container but is being allowed to fall to the ground. In addition, doubling the number of blades and keeping the cutting edges in the same plane so that both blades share equally in the work increases the time the blades can be used before they have to be sharpened again. While it then becomes necessary to sharpen twice as many blades, doubling the number of blades on a drive shaft does not substantially increase the time required for removing them from the shaft to sharpen them and then putting them back on again. Thus, the total increase in work output and in the quality of the result is of greater benefit than the time lost in the complete sharpening procedure.